Rechargeable batteries: Everything you need to know

With the massive presence in every corner of the world of computers, digital cameras and MP3 players, rechargeable batteries are increasingly used. The main reason is the fact that the disposable batteries are expensive for those who need a constant use of them.

This article will show the main characteristics of rechargeable batteries, including capacity, the most common types of rechargeable batteries and chargers to be used.

What are the rechargeable batteries?

One of the most common reasons why discard a battery is when charge runs out or is in an insufficient energy level, or weak. With a rechargeable battery, enough with using the adequate device, called charger, so that the battery is loaded again and it can be used again.

It is important to remember that a conventional battery cannot be recharged, although there are devices that claim to serve for it, the chemical composition of this type of battery it is not suitable to be recharged. If we try to recharge a conventional battery, chemicals inside the battery will be filtered. We must remember that these chemicals are potent, and may even poisoning. It is also possible that the batteries explode, causing irreparable damage to the devices and injuries to people.

The market offers basically two types of rechargeable batteries: NiCd and MiMH:

Batteries NiCd (Nickel Cadmium)

Also called NiCd, this is the type of rechargeable battery that first appeared on the market. Normally, NiCd batteries are cheaper. However, they have shorter lifespan, as well as less capacity.

NiCd batteries can suffer from a problem called “memory effect”. When that happens, the battery stops being fully charged by their chemical composition and sending a signal that charging is complete. To better understand, imagine that a battery has a memory effect reaches 10% capacity. This indicates that the load will be 90%, since the battery indicate that the remaining 10% are already loaded.

The memory effect occurs when load residues on the battery induce the formation of small blocks of cadmium. The best way to avoid this problem is not recharge the battery when it is still loaded. In this case, it is best to wait until the battery is completely depleted, and cannot be used in any device.

NiCd batteries are increasingly obsolete, because besides the memory effect of its smaller capacity and shorter service life, this type of battery is highly polluting, since cadmium is a highly toxic and harmful chemical element for environment.

NiMH Batteries (Nickel-Metal Hydride)

Also they called Nickel Metal Hidreto, the NiMH are the battery type most commonly used, since they offer greater capacity, longer life and endure more recharge if compared to NiCd (depending on the manufacturer, that cannot be true).

Moreover, they are less polluting, and does not use heavy materials such as cadmium. Another advantage of this type of battery is the absence of memory effect.

Over time, these batteries will be replaced by Li-ion, far more capable.

Batteries Li-ion (lithium ion)

The lithium ion batteries (Li-ion) are lighter, have a high energy holding capacity, and high resistance to shock. They do not have the problem of memory effect and support a large number of charging cycles.

Its main problems lie in its rapid degradation and sensitivity to high temperatures, which may result in its destruction by inflammation or even explosion. At the moment they are more expensive than Nickel.

The capacity of rechargeable batteries

Basically, the capacity battery power is measured in milliamps per hour, whose acronym is mAh. Thus, it is necessary to know the consumption of each equipment to measure the duration of use of the battery in the device.

As an example, imagine that you have an MP3 player that uses a AAA battery and consumes 200 mA. If the battery capacity of 1000 mAh, it will last:

1000/200 = 5 hours

It is clear that this calculation is not accurate, since other factors and specifications may to increase consumption.

Chargers

As the name implies, the chargers are devices responsible for recharge batteries that can be recharged. The procedure is simple: just place one or two pairs of rechargeable batteries in the device and connect it to the mains.

This way of working makes we think that the battery power is made through the transfer of energy to the battery, just as we fill a bottle with water from a faucet. In fact, it is not as simple as that.

The battery recharging process involves passing an electric current through them so that the energy is “captured” and stored. The higher the current (faster chargers), the shorter the time required for recharging.

However, a too faster recharge makes the heat generation increases, and thus, the possibility of an explosion, fact that we can avoid by purchasing a charger that is capable by a light or sound, clearly indicate when the battery is fully charged.

The most common chargers are those who perform a slow charge, the advantages of this type are in the price and the drastic reduction in the risk of super-heating of the batteries. Besides that, the batteries end up having longer life.

In choosing a charger, choose the models that work with both NiCd and NiMH. Give preference to those who break the current (actually, maintain a low current to keep the energy in the battery) when charging is complete.

Beware of fake rechargeable batteries

With the increasing use of rechargeable batteries, the pirate industry is not limited to falsify conventional batteries. Depending on the location, is much easier to find fake batteries than real batteries. The reason for such distribution is simply: offer and demand.

Counterfeit batteries, be standard or rechargeable, can bring problems. These batteries should be avoided, inter alia, for the following reasons:

The actual capacity offered is smaller than the reported capacity in the packaging

Not using the specified technology, for example, instead NiCd, is used NiMH

May have lower quality and discharge more faster

You may offer a shorter lifespan than expected

Battery counterfeiters are very skilled in this “art”. Still, it is possible to know when a stack is false by observing a number of features. For example, it is common for pirates to announce a AA battery that offers a very high number of mAh when, indeed, the maximum achieved by this technology is very lower.